A scheme to manipulate Wall Street’s fear gauge, VIX, poses risk to the entire equity market and costs investors hundreds of millions of dollars a month, according to an “anonymous whistleblower.”

A law firm representing the individual told U.S. financial regulators about the alleged manipulation and urged them to investigate before additional losses are suffered.

The Washington-based law firm which represents an anonymous person who claims to have held senior roles in the investment business, told the Securities and Exchange Commission and Commodity Futures Trading Commission on Monday that he discovered a market manipulation scheme that takes advantage of a widespread flaw in the Chicago Board Options Exchange (CBOE) Volatility Index (VIX).

The CBOE Volatility Index measures the cost of buying options and is the most widely followed barometer of expected near-term stock market volatility.

“The flaw allows trading firms with advanced algorithms to move the VIX up or down by simply posting quotes on S&P options and without needing to physically engage in any trading or deploying any capital,” it said in a letter.